Which of the following statements about the carbon cycle is not true?

carbon dioxide used by plants comes from the atmosphere.
plants need carbon to grow.
plants consume carbon through transpiration.
carbon from decomposed plants is a source of fossil fuel.

plants consume carbon through transpiration.

Explanation:

Transpiration is simply a process whereby plant loses water to the environment in form of moisture or vapor. It can happen via the stomata, lenticels or cuticles of plants.

Transpiration has nothing to do with plant's consumption of carbon. Plants fix carbon into their system through the process of photosynthesis during which CO2 in the atmosphere is utilized to synthesize glucose.

Carbon is an important element for all living organisms, hence, plants also needs carbon to grow.

Carbon from decomposed plants is truly a source of fossil fuel. Decayed plants form combustible geologic deposits deeply buried in the soil and ends up forming coal, crude oil, natural gas and other forms of fossil fuel.

Therefore, the only untrue option is the one claiming that plants consume carbon through transpiration.